zipl: Fix dependency generation in zipl/boot
zipl: Fix dependency generation in zipl/boot

When adding new header from zipl/include to a .c file within zipl/boot
a compiler error appears

	stage3.c:16:10: fatal error: zipl.h: No such file or directory
	 #include "zipl.h"
	          ^~~~~~~~
	compilation terminated.
	  CC      zipl/boot/stage3.o

This is because the rule to generate dependencies (*.o.d) does not use
the CFLAGS_BOOT. Thus it cannot find the header and fails. Note this
only applies to the dependency generation, the actual build succeeds.

To fix this rename the CFLAGS_BOOT to ALL_CFLAGS. Using ALL_CFLAGS
instead of e.g. ALL_CPPFLAGS is important to also overwrite flags given
on the commandline via OPT_FLAGS, e.g.

	make V=1 OPT_FLAGS="-D__FOO__"

While at it also remove the unused and wrong '-D__ASSEMBLY__'.

Fixes: 5a6605fe ("zipl: Ensure that boot loader CFLAGS are not overwritten")
Fixes: aa913b1e ("build process: Add automatic dependency generation")
Signed-off-by: Philipp Rudo <ebc9ed60c9e1dc6a17c00cf7f6009c740d3c3928@linux.ibm.com>
Reviewed-by: Stefan Haberland <dec981e3bbb165d021029c42291faf06f59827c1@linux.ibm.com>
Signed-off-by: Jan Höppner <96138615ab4af0813785fa10d283f3d37eca3b78@linux.ibm.com>

ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools,ibm-s390-tools/s390-tools